Field
This example implementations described herein relate generally to computer systems and more particularly, to data caching technologies in converged system that may execute application processing, server processing, and storage processing in the same, shared hardware.
Related Art
Caching technology is known in the related art. Generally, a related art storage system includes a cache memory and data stored in the storage device, such as a hard disk drive, is cached to the cache memory. One related art system includes technology to use a Solid-State-Drive (SSD) installed on a server as a cache for the data stored in a storage system connected to the server.
Generally, related art converged systems include of one or more hardware nodes and storage capacity provided by storage devices associated within each of the nodes forms a resource pool. These resources of the resource pool can be shared across the nodes. Several converged system products are known in the related art. In a related art converged system application, server processing and storage processing are all executed in the same hardware.
In the related art converged system, two address spaces must be managed by a single node when the processing of the server and the processing of the storage is executed on the same hardware node. The first address corresponds to the address of LU (Logical Unit), which is recognized by the server process. This first address is referred to herein as a virtual address space. The second address corresponds to the address of the storage device. This second address is referred to herein as an internal address space.
The Logical Unit (LU) is created from the capacity pool formed by the storage device associated with all of the nodes. As a result, each virtual address space may generally be different from the internal address spaces. If the related art system consists of only one large system (i.e., a single node), caching using the virtual address spaces has the same effect as caching using the local address spaces. However, if the related art system consists of two or more nodes, different effects can occur, depending on whether the virtual address spaces or the local address spaces are used for caching.
For example, when caching is performed using only the internal address spaces in a converged system having more than one node, data access of a storage device in a different node requires communication between nodes, even in cache hit cases, which can cause decreased performance inconsistent latency.
Alternatively, when caching is done using only virtual address space in a converged system having more than one node, an application running on one node can only use the cache area of the same node. For the system, this may result in inefficient allocation of the cache area. In particular, low priority applications may consume the cache area, decreasing the effectiveness of the cache area.